212 University of California Publications in Zoology [Vou.9 
other way than by devising and using some means of capturing 
organisms in these depths if they oceur there. On the other 
hand, if it is desirable to know whether eggs that develop natur- 
ally in sea-water will develop at all, or in some modified way, in 
water that contains only one of the minerals found in normal 
sea-water, there is one possibility and only one of finding out, 
and that is to place undeveloped eggs in the particular kind of 
water about which the question is asked and see if they develop. 
One method leads to knowledge of one sort, another to 
knowledge of another sort, generally speaking. Apparently the 
question of the greater importance of one method as against 
another could arise only as a sequel to a judgment already 
reached that one kind of knowledge is more important than 
another. If the object of biological research is held to be ‘‘to 
know, to understand organic things’’ (Ritter, 1908), if a par- 
ticular biological undertaking has the end in view of getting as 
much knowledge as is possible about the organisms in a re- 
stricted area of the earth, there can be no partiality shown for 
one method over another. Each and every known method will 
be invoked as far as practicable and prized without stint for 
the particular thing it can do. 
As a matter of fact the sharp distinction frequently made 
between the experimental and the descriptive methods in biology 
has less scientific validity and less practical utility than the 
distinction between field, or out-in-nature methods and labora- 
tory methods. Observation is surely essential in laboratory 
investigations no less than in field investigations. And no one 
can give an intelligible account of what he has accomplished 
either in laboratory or field, without description of some sort. 
Experiment is likewise resorted to almost if not quite always in 
work done with sufficient care and intelligence to meet the 
requirements of modern biology, in field studies no less than in 
laboratory studies. The testing of different kinds of closing 
nets, for instance, in the effort to find at what depth a par- 
ticular species of pelagic organism occurs in greatest abundance, 
is as certainly an experiment as is the testing in a laboratory of 
the effect of light of different intensities on the same species. 
But there comes to view a distinction between out-in-nature 
